Here's a question for you, fellows: Has there ever, in the history of the world, been a reported case of a fair-sized skyscraper (say, ten or more storeys) sort of just falling over? I don't mean during an earthquake or a bombing raid or when it's been demolished, but just in general, or on a
particularly windy day? Whenever I'm at the top of a really tall building I swear I can feel it swaying, and I'm pretty sure it's going to topple over.

Has a skyscraper ever just...whoopsied? And were there people in it? I ask about tall buildings as the idea of one of those short squat things crumbling to the ground just doesn't fill me with much dramatic imagery.

On the contrary, tall buildings sway by design in the wind to prevent toppling.

AFAIK, no skyscraper has ever fallen over due to a structural design flaw, at least in the US. However, back in 1978, the recently completed Citibank building had about a 50% chance of collapsng in winds of moderate hurricane force (about 78 mph). Supports beams had been bolted instead of welded. Coincidentally, a hurricane was on it's way when secret repairs were begun to correct these problem. It didn't fall over. If it HAD, the domino effect would have levelled about 156 blocks by one estimate.

Soon after the John Hancock Tower in Boston was built it was discovered that there was a very real danger of it tipping over in a high wind. To prevent this, a large (approx. 40 tons) weight suspended on springs was placed at the top floor of the building. If the tower swayed in one direction, the inertia of the weight would halt it and swing it back. This allowed the tower to sway slightly in the wind, but prevented it from overbalancing and toppling.

Incidentally, the engineers had initially worried about the building toppling in the direction of its broad side, and had taken steps during construction to prevent this. The surprise came afterward when it was discovered that the real danger was in the buiding falling along its narrow side, which necessitated the weights in the top floor.

Back in college I did an internship at WZLX radio in the 42ns floor of the Hancock. During storms you could hear the building creeeeeak back and forth. Creepy.

Or, you could read this book: Why Buildings Fall Down: How Structures Fail by Matthys Levy and Mario G. Salvadori. They also wrote one on why building stay up, but that's not as much fun.

The book is a very readable account (for a lay-person like, well, me) of famous structural collapses. I've lent my copy to quite a few friends, none of whom are engineers, and they've all enjoyed it too.

In New York City, fairly large buildings have occasionally collapsed due to years of neglect or poor maintenance. I don't know how large the largest one was, but I remember seeing on the news a five story apartment building had collapsed a few years ago.

IIRC, the Citibank problem was a design defect. Engineers had designed the building to withstand wind directly to the front/back/sides. With its cross shape, no one had bothered to test winds of a 45 degree angle.

Originally posted by Sublight
Soon after the John Hancock Tower in Boston was built it was discovered that there was a very real danger of it tipping over in a high wind. To prevent this, a large (approx. 40 tons) weight suspended on springs was placed at the top floor of the building. If the tower swayed in one direction, the inertia of the weight would halt it and swing it back. This allowed the tower to sway slightly in the wind, but prevented it from overbalancing and toppling.

The same sort of tuned mass dampers were also installed in Citicorp Center, and in the towers of the Akashi Kaikyo (sp?) bridge in Japan, which survived the Kobe Earthquake already.

As for the Hancock, it also had a lot of extra structural support squezed into it. The tuned mass dampers were added earlier to correct excessive swaying. The entire story will probably never be fully known, as everyone involved had to sign non-disclosure agreements. Those problems were also unrelated to the problem that made the windows fall out, and the one that threatened to destroy Trinity Churh across the street.

I'm sorry to necro an old thread, but I just read this thread and it hit me how eerie it is that this thread about buildings falling over took place like 2 weeks before 9/11.

Weird ... golgotha's last post here was on 9/11 at 5:38 am Saudi Arabian time ... alas, this was in 2003, almost had the makings of a GREAT conspiracy theory ... the Chicago Reader trying to make the Sears Tower the tallest building in the USA again ...

The Millennium Tower in San Francisco hasn't fallen yet, but due to the designers' and builders' failure to push the support pilings all the way down to bedrock, it has started leaning, and the foundations have started cracking. There are theoretically supposed to be some possible solutions, but if it ever goes over it won't go by itself, since it is right in the middle of a bunch of other buildings. With any luck it will fall to the SE and take out the Salesforce tower (at night and when no-one is in either building and no-one gets hurt).

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